Heretofore, for example, an electromagnetic contactor shown in FIG. 5, FIG. 6(a) and FIG. 6(b) is known as an electromagnetic contactor having a contact mechanism that includes a pair of fixed contacts disposed to maintain a predetermined interval and a movable contact that is connectable to and detachable from the pair of fixed contacts (refer to PTL 1).
An electromagnetic contactor 101 shown in FIG. 5 includes a main body case 102 having a two-part structure of an upper case 102a and lower case 102b. A contact mechanism CM is installed inside the upper case 102a. The contact mechanism CM includes a pair of fixed contacts 103, disposed to maintain a predetermined interval in a longitudinal direction (the left-right direction in FIG. 5) in the upper case 102a, and a movable contact 104 disposed so as to be connectable to and detachable from the fixed contacts 103. Fixed contacts 103a and 103b are respectively provided on the pair of fixed contacts 103. Also, the movable contact 104 extends in a longitudinal direction (the left-right direction in FIG. 5, the direction in which the pair of fixed contacts 103 are disposed), and movable contacts 104a and 104b that contacts with the fixed contacts 103a and 103b are provided at two ends of the movable contact 104 in the longitudinal direction.
Meanwhile, an operating electromagnet 105 that drives the movable contact 104 is disposed in the lower case 102b. The operating electromagnet 105 includes a fixed iron core 106 and a movable iron core 107 disposed above and opposing the fixed iron core 106. Further, an electromagnetic coil 109 disposed and wound in a coil holder 108 is fixed in a central bottom portion of the fixed iron core 106, and a return spring 110 that biases the movable iron core 107 in a direction away from the fixed iron core 106 (an upward direction) is disposed between the upper surface of the coil holder 108 and the movable iron core 107.
Also, a contact holder 111 is connected to the upper end of the movable iron core 107. An insertion hole 111a is formed in the upper end side of the contact holder 111, and the movable contact 104 is disposed in the insertion hole 111a so as to be able to move in a vertical direction. The movable contact 104 is formed of a plate-form member that is long and thin in a longitudinal direction, and a portion substantially central in the longitudinal direction is urged downward and held by a predetermined urging force of a contact spring 112 installed inside the insertion hole 111a. Further, when the movable contact 104 contacts the fixed contacts 103, the contact spring 112 applies a predetermined contact pressure to the fixed contacts 103.
In the electromagnetic contactor 101 formed in this way, when the electromagnetic coil 109 of the operating electromagnet 105 is in a non-excited state, and is in a released state; no electromagnetic suctioning force is generated between the fixed iron core 106 and movable iron core 107, and the movable iron core 107 is biased upward in a direction away from the fixed iron core 106 by the return spring 110. Further, the contact holder 111 connected to the movable iron core 107 is held in a current interrupting position (final state of release) by coming into contact with a stopper 113. In the current interrupting position, as shown in FIG. 6(a), the movable contacts 104a and 104b provided on the movable contact 104 are separated upward from the fixed contacts 103a and 103b respectively provided on the pair of fixed contacts 103, whereby the contact mechanism CM is in an opened state.
On the electromagnetic coil 109 of the operating electromagnet 105 excited when the contact mechanism CM is in an open state, to create an engaged state, a suctioning force is generated between the fixed iron core 106 and movable iron core 107, and the movable iron core 107 is suctioned downward against the return spring 110. Because of this, the movable contact 104 held by the contact holder 111 descends, and the contact mechanism CM changes to a closed state. In the closed state, as shown in FIG. 6(b), the movable contacts 104a and 104b provided on the movable contact 104 contacts the fixed contacts 103a and 103b respectively provided on the pair of fixed contacts 103 with the contact pressure of the contact spring 112, and current input from an external input terminal 103c is supplied to an external connection terminal 103d through the fixed contact 103, movable contact 104, and fixed contact 103.
Further, when the electromagnetic coil 109 of the operating electromagnet 105 changes to a non-excited state, the movable contact 104 carries out an operation reverse to the heretofore described operation, the contact mechanism CM changes to an open state, and the contact holder 111 connected to the movable iron core 107 is held in a current interrupting position (final state of release) by coming into contact with the stopper 113.